cd14965: 7tm_Opsins_type1 (this model, PSSM-Id:320096 is obsolete and has been replaced by 410629)
type 1 opsins, member of the seven-transmembrane GPCR superfamily
This group represents the microbial rhodopsin family, also known as type 1 rhodopsins, which can function as light-dependent ion pumps, cation channels, and sensors. They have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. Members of the type I rhodopsin family include: light-driven inward chloride pump halorhodopsin (HR); light-driven outward proton pump bacteriorhodopsin (BR); light-gated cation channel channelrhodopsin (ChR); light-sensor activating transmembrane transducer proteins, sensory rhodopsin I and II (SRI and II); light-sensor activating soluble transducer protein Anabaena sensory rhodopsin (ASR); and other light-driven proton pumps such as blue-light-absorbing and green-light absorbing proteorhodopsins, among others. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins.
Jiyao W et al.(2023). "The conserved domain database in 2023.",